﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace _1._1_area
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("请输入半径的长度：");
            double r = Convert.ToDouble(Console.ReadLine());
            const double PI = 3.1415926;
            double S = PI * r * r;
            double C = PI * 2 * r;
            Console.WriteLine("周长是:{0}\n面积是:{1}", C, S);
            Console.ReadLine();
        }
    }
}
